<?php

    function removeSpecialChars($string){
      //List (Array) of special chars
	  $pattern = array("/([áàãâä])/","/([ÁÀÃÂÄ])/","/([éèêë])/","/([ÉÈÊË])/","/([íìîï])/","/([ÍÌÎÏ])/","/([óòõôö])/","/([ÓÒÕÔÖ])/","/([úùûü])/","/([ÚÙÛÜ])/","/(ñ)/","/(Ñ)/","/(ç)/","/(Ç)/","/([\\'\\\"\\^\\~\\;\\:\\°\\?\\&\\*\\+\\@\\#\\$\\%\\!\\\\\\/\\(\\)\\|\\=\\.\\,])/");

      //List (Array) of letters
      $replacement = array('a', 'A', 'e', 'E', 'i', 'I', 'o', 'O', 'u', 'U', 'n', 'N', 'c', 'C', '');
    
      return preg_replace($pattern , $replacement, $string);
    }

echo removeSpecialChars("áçõ/\\?&");